Device for distant firing of explosive charges



Dec. 27, 1938. M. SCHLUMBERGER 2,141,827 v DEVICE FOR DISTAT FIRING 0F EXPLOSIV CHARGES Filed. Jan. 24, 193e u Patented Dee. 27, 193s DEVICE FOR DISTANT FIRING F EXPLOSIVE CHARGES Marcel Schlumberger,

Schlumberger, Paris, France Application January 24, 1936, serial No. '60,721

Paris, France, assigner to Societe de Prospection Electrique, Procedes France, a corporation of In France November 16, "1935 1,0 Claims.

In boring or other operations for Working petroleum beds it may happen that it is necessary to fire successively a plurality of explosive charges at a distance and at depths which may be greater than 3,'000 feet. This is particularly the case when it is intended to take cores or samples on the lateral wall of bore holes by means of a device such as described in U. S. Patent No. 2,055,506,

September 29, 1936, for a Core taking device. It l0 is also the case when it is intended to perforate the wall of a casing at the level of underground petroleum layers for working those layers by means of bullet perforators of any known type. In both cases the problem to be solved consists in making it possible to. re successively, at will and with any single given device (sample-taking device or perforator) the various gun-powder or explosive charges serving for the ejection of the bullets, and this by means of a single electrical conductor for controlling those successive firing operations.

The present invention relates to a `device where-- by this result may be attained in a simple and efficient manner, and without danger, by means of resisting electric wires imbedded in the mass of gun-powder or explosiveand heated by an electric current. However, the application of the present invention 4is not limited to the above mentioned cases but can be extended to other cases distance. A

The term lament will be used herein to designate the resisting electric wires imbedded in the y explosive or in the gun-powder and the heating Kof which causes the desired deiiagration, although these wires are not necessarily caused to melt during the passage of the current or even under the action of the explosion. On the other hand, the expression to blow up by meanspf a lament will be used for the operation consisting in causing a current to pass through the fiilan'ient, suicient for causing the deagration in the corresponding chamber.

-It has been already proposed, in thelabove mentioned patentfand for solving this problem, to arrange in the various detonation chambers filaments having different characteristicsa and mounted in parallel between an insulated conductor'body and the mass formed by the body of 5o the `device itself arranged in the conductive mud of the bore hole. By causing increasing current intensities to pass through this co'nductor the filaments are successively and selectively blown up. In practice this arrangement has been found defective, for as soon as the first shot is red the where successive firings are to be eiected at a conductive 'mud in the bore hole enters, by the Y' force of its own pressurethe chamber where the defiagration has taken place and connects the line with the vground at the point` where the filament has been blown up. 'I'hus it is impossible to blow up the next filament.

AI t is the main objecJ of the present invention to provide a remedy for this inconvenience and ,to that end detonating laments of progressively decreasing heating capacities, for instance of increasing sizes in cross-section, are connected in series in the electric circuit, which can comprise only a single conductor with its return conductor,

one of said filaments being placed in each explosion chamber. In the case of boring works and of filaments which are `effectively blown up the connection with the ground which occurs at the point where each deflagration has occurred ceases to be detrimental, as in the foregoing case, and on the contrary the same is indispensable, since it is that which automatically re-establishes the interruption of the circuit through the ingress of the conductive mud into the corresponding detonation chamber.

If this grounding does not occur readily it 1s possible to provide furthermore, according to this invention, devices adapted to cause an effective `grounding under the action of the deflagration itself. These devices can operate, forinstance, through direct engagement-under the action of the pressure caused by the deflagration and if necessary with the obliteration of an intermediate insulation-of the conductor leading to each filament with one of the walls of the corresponding vdetonation chamber.

The present invention offers the advantage of requiring only a single'conductor, not only for connecting the point from which the-defiagrations are controlled above ground, for instance) with the device in which the deflagrations are produced (in the bore hole and at any depth), but even in the body of this device for causing the successive rings of a plurality of charges; as a result whereof the construction andv the assembly of the device are simplied. .p

In practice and because of the range of laments which can be used, it will be-easilypossible to-control four, five or more successive deflagrations by means of va single conductor.

On the other hand, as the organizations which 1 effect boring operations have generally at their disposal cables with several conductors, it `will vbe possible, according to the invention, to provide devices (perforator or sample-taking device or the like) with a certain number of chargeswhich can be .lired separately through conductors of the cable.

Other features of the invention will appear from the following description.

In the appended drawing several embodiments of the invention have been shown diagrammatically by way of non-limitative examples.

In this drawing:-

Figure 1 is a diagrammatical view showing the connection of filaments in series according to the invention. y

Figure 2 is a longitudinal sectional view of a bullet perforator according to the invention.

Figure 3 is a longitudinal sectional view of a bullet sample-taking device according to the invention. I

Figures 4 and 5 are respectively arr enlarged cross sectional viewandan enlarged profile view of a detail of the device shown in Figure 3.

In Figure 1, I is the insulated electric conductor which connects the pointk at which the firing is controlled (above ground, for instance) to-"the point where the firing must be effectedy each of the several y("sarnplel taking device or perforator, for instance,

` described in co-pending application for patent immersed in the mud-of a bore hole). vlin cir'- cuit with this insulated conductor are mounted in series a plurality of filaments, yfour forginstancel (3, 4, 5, 6); one of said filaments being located in each of the explosion chambers, and said laments being progressively of increasing diameter fromone end to the other of the series, as shownin Fig. 1. The lower end of the lower filament 3 is grounded at 2; the ground mass being formed, for instance, by the metal body of the device itself which, being immersed in the conductive mud, insures a goed grounding. If the conductor I lis then connected with one of the poles of a'. source of current, the other pole of which is grounded, so as to cause currents of successively increasing intensities lto pass through this conductor, filament. 3 is i'lrst blown up, thus causing an explosion in one of the chambers. This explosion automatically causes, through the rushing into the explosion chamber of the conductive fmud, for instance, the

groundingwof the end of the viilament 4 at "Lv Then, by causing av current of a stronger intensity to pass, the filament 4 is blown up in its turn, thus causing an explosion. in the corresponding chamber, followed by the grounding ofthe filament 5 at 8, and s o on.

` Figure 2 shows a bullet perforator of the type for a Core taking device, Serial Number 60,725, led January 24, 1936. The perorator comprises a cylindrical steel block I I in which areannu'- lar detonation chambers I2, I3, It and so on, one beneath the other. Into these detonation chambers are screwed the tubes I5 which form the guns serving to eject perforating bullets I6. The mouths of these guns are not located one directly beneath the next above, but-are preferably disposed helically around the' cylindrical body. The explosive is placed in the chambers I2, I3, I4 which enclose each one'of the' gun tubes I5, and in these chambers the filaments are located. Inasmuch as these filaments progressively decrease in cross section from the topmost downward, asshown in- Fig. 1, the vresist-'- ance thereof correspondingly increases in the same order.

The filament of the llower chamber is connected at its lower end with the mass of the cylindrical body II. The several filaments are connected with one another and with the current supplying conductor through conductive deviges which will be now described.

As shown in Fig. 2, the chambers I2, I3, I4 are in communication by vertical bore holes, in which are placed the connecting conductors. These" are formed, as shown, each of two plugs I7, i8, inserted or screwed one into the other so as to leave an annular space between them and the wall of the containing hole. But, of course, any other construction suitable for the purpose may be adopted. Each pair of plugs has two Valve-heads I9, I9', one at each end, which rest when closed upon a valve-seat, 20 or 2|, formed in the metallic body Iljand coated with a rubber Solution, or equivalent insulating substance 2li', 2|', which insures electrical insulation of the conductor I'l-I8. Thus in eachy explosion charnber are two valve-heads, one at the top and the other at the bottom thereof, the two being electrically connectedv together by the detonating filament 35. Valve-head I9 inthe upper explosion chamber isA attached directly to the current supplying cable I', which is suitably insulated and which serves not only to supply the detonating current but also to support the entire body I'I.

The apparatus ybeing immersed in the quasi yfluid mud oi. the drill hole at the level where it is to be used', if current of the proper intensity is supplied to conductor I, the filament of smallest cross section, which is in the lowermcst chamber, is blown, causing deflagration of the explosive.- in that chamber and the. consequent expulsion of bullet I6 from gun I5 of that chamber. On the other hand, this explosion forces the valve-heads I9, I9' of that chamber against their respective seats, thus crushing down the rubber solution 20', 2l and establishing metallic contact between the valve-heads and their seats.

After the expulsion of the projectile the mud .f

in the bore hole, being under high pressure, forces its way into the tube ofthe gun I5 and into `the explosion chamber, lling the same and thus insuring the grounding of the upper valve-,head I9. If then a4 current of greater intensity than the rst -detonatng current is sent through con` ductor t, the second filament from the bottom will be blown, thereby exploding the charge 1n the corresponding chamber and causing a repitition of the above described phenomena; and so on.

In Figure Ln-which shows an embodiment of a bullet sample-taking device as described inthe above rrientioiziedv patent application, Serial Num- Y ber 60,726, the firing is effected in a similar manner. Ho-wever due to the presence in the detonation chamber of devices such as the cable or cables retaining; the bullet, or because this detonation chamber is located behind the axis :ve-y of the sample-taking device, it may be that transmission of the current is not possible along said axis :1f-y. In that case insulated conductors 23, 24, 25 may be provided, which supply current to the valve heads 26 and 30 arrange-d as previously described in the bottom of each detona- `tion chamber such as 2l. Openings4 are provided the lcylindrical body II of the sample-taking device in order to permit the mounting of these different insulated members and these openings 'are closed. either through threaded plugs 28 or through screwed pieces 29.v

The valve heads 2li-and 30 which are, as previously described, insulated from the body of the device I`I by a rubber solution, for instance, come to rest at their edge (Figures 3, 4 and 5) against metal pieces 3| and 32 in form of an arc of a circle, said metal pieces being applied against an annular piece of cardboard `33- mounted on the bottom of the detonation chamber 21. The firing filament 35 is directly connected with the annular pieces 3|-32 (Figure 4).

Y As in the foregoing case, the filaments 35 are of progressively increasing diameter from the lowermost upwards, so that the deilagrations are produced successively from the bottom to the top when sending increasing current intensities. Under the action of the deflagration produced in one of the chambers, the ejection of the bullet causes, as previously described, the rushing in of the mud whichthen seats the valve head 26. In order to insure a still more eflicient seating of the valve headsa hole 34 (Figs. 4, may be provided in the piece of cardboard 33 at the place where it is covered by the conductor element 3|. Under the action of the deflagration, the material of the element 3| which lies opposite the hole 34, is pressed in or bulged and thus \brought into contact v vith the metal bottom of the detonation chamber 21, thus insuring a perfect seating.

Of course, many changes can be made in the above described devices without'departing from the scope of the invention. Furthermore, the invention can be applied to systems of sampletaking device or perforator other than those herein described.

What I claim is:

1. In a device for successively firing a plurality of explosive charges at a distance through electrical means, a series of chambers each containing an explosive charge, a filament in each chamber surrounded by the explosive charge, the successive filaments being of a sensitiveness varying in the same direction from one filament to the next, means for connecting electrically the successive filaments in series, so as to form an electric circuit, and means for passing electric currents of progressively increasing intensities through the filaments.

2. In a device for successively ring a pluralitg of explosive charges ata distance through electrical means, a series of chambers each containing an explosive charge, a filament in each .chamber surrounded by the explosive charge, the

filaments being of progressively increasing diameters, means for connecting electrically the successivelaments in series so as to form an electric circuit, and means for passing electric currents through the filaments.

3. In a" device for successively firing a plurality of explosive charges at a distance through electrical means, a series of chambers each containing an explosive charge, a filament in each chamber surrounded by the corresponding explosive charge, the filaments having different and progressively increasing heating capacities, means for connecting electrically the successive laments in series, so as to form an electric circuit, and means for passing electric currents of progressively increasing intensities through the filaments.

4L In a device for successively ring a plurality of explosive charges at a distance through electrical means, a series of chambers each containing an explosivecharge, a filament in each chamber surrounded by the explosive charge, the :lilaments being of progressively variable heating capacity, means for connecting electrically the successive filaments in series so as to form an electric circuit, with return to the mass, means for passing electric currents through the filaments,

. and means for ,automatically grounding the circuit at the point where an interruption the'reof is produced through the melting of the lament after each explosion.

5. Apparatus for electrically' firing successively at a distance a plurality ofexplosive charges, said apparatus comprising: a metallic supporting body adapted for immersion in a quasi fluid medium under high pressure, such as the mud of a bore hole; a series of chambers for containing each anexplosive charge; an electric circuit for controlling theexplosions by means of a single conductor; filaments of progressively increasing size, one in each of said chambers and connected in series in said circuit; means for automatically effecting the grounding of said circuit at the point where each explosion takes place, said means being actuated vby the inrush of said quasi fluid medium to effect contact of said conductor -with the body of thejapparatus.

6. Apparatus for electrically ring successively at a distance a plurality of explosive charges,

said apparatus comprising; a metallic supporting body adapted for immersion in a quasi fluid medium under high pressure, such as the mud of a-bore hole; a series of chambers for containing each an explosive charge; an electric circuit for controlling the explosions by means of a single conductor; filaments of progressively increasing size, one in each of said chambers and connected in series vin said circuit; an insulating substance between the body of the apparatus and said conductor at its entrance into and. at its exit from each explosion chamber; means for automaticallyv grounding said conductor at the point Where each explosion takes place, said means being actuated by destroying said insulation and thereby effecting contact of said conductor with said metallic body.

7. Apparatus as specified in claim 6 wherein the means for automatically grounding the conductor at the point Where an explosion occurs comprising valve-heads for each chamber where the conductor enters and leaves it; an interposed insulating substance; and actuating means for bringing said valve-heads into such forceful contact with their respective seats as to destroy the interposed insulation'.

8. Apparatus as specified in claim 6, wherein the means for grounding the, conductor at the point Where an explosion occurs comprises valveheads for each chamber placed where tne conductor enters and leaves the same, and a pair of plugs fitted together for connecting the valveheads of adjacent chambers.

i 9. Apparatus for electrically firing successively at a distance-a plurality of explosive charges, said apparatus comprising a cable composed of a plurality of electrical conductors, each of said conductors having in its circuit a series of detonating filaments of progressively increasing sizes. I

10. Apparatus for electrically firing successively at a distance a plurality of explosive charges, said apparatus comprising anelectric circuit and a series of detonating filaments forming part of said circuit, said filaments having different and progressively decreasing capacities.

MARCEL SCHLUMBERGER.. 

